2 * linux/kernel/signal.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
8 * 2003-06-02 Jim Houston - Concurrent Computer Corp.
9 * Changes to use preallocated sigqueue structures
10 * to allow signals to be sent reliably.
13 #include <linux/config.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/smp_lock.h>
17 #include <linux/init.h>
18 #include <linux/sched.h>
20 #include <linux/tty.h>
21 #include <linux/binfmts.h>
22 #include <linux/security.h>
23 #include <linux/syscalls.h>
24 #include <linux/ptrace.h>
25 #include <linux/posix-timers.h>
26 #include <linux/signal.h>
27 #include <linux/audit.h>
28 #include <asm/param.h>
29 #include <asm/uaccess.h>
30 #include <asm/unistd.h>
31 #include <asm/siginfo.h>
34 * SLAB caches for signal bits.
37 static kmem_cache_t *sigqueue_cachep;
40 * In POSIX a signal is sent either to a specific thread (Linux task)
41 * or to the process as a whole (Linux thread group). How the signal
42 * is sent determines whether it's to one thread or the whole group,
43 * which determines which signal mask(s) are involved in blocking it
44 * from being delivered until later. When the signal is delivered,
45 * either it's caught or ignored by a user handler or it has a default
46 * effect that applies to the whole thread group (POSIX process).
48 * The possible effects an unblocked signal set to SIG_DFL can have are:
49 * ignore - Nothing Happens
50 * terminate - kill the process, i.e. all threads in the group,
51 * similar to exit_group. The group leader (only) reports
52 * WIFSIGNALED status to its parent.
53 * coredump - write a core dump file describing all threads using
54 * the same mm and then kill all those threads
55 * stop - stop all the threads in the group, i.e. TASK_STOPPED state
57 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
58 * Other signals when not blocked and set to SIG_DFL behaves as follows.
59 * The job control signals also have other special effects.
61 * +--------------------+------------------+
62 * | POSIX signal | default action |
63 * +--------------------+------------------+
64 * | SIGHUP | terminate |
65 * | SIGINT | terminate |
66 * | SIGQUIT | coredump |
67 * | SIGILL | coredump |
68 * | SIGTRAP | coredump |
69 * | SIGABRT/SIGIOT | coredump |
70 * | SIGBUS | coredump |
71 * | SIGFPE | coredump |
72 * | SIGKILL | terminate(+) |
73 * | SIGUSR1 | terminate |
74 * | SIGSEGV | coredump |
75 * | SIGUSR2 | terminate |
76 * | SIGPIPE | terminate |
77 * | SIGALRM | terminate |
78 * | SIGTERM | terminate |
79 * | SIGCHLD | ignore |
80 * | SIGCONT | ignore(*) |
81 * | SIGSTOP | stop(*)(+) |
82 * | SIGTSTP | stop(*) |
83 * | SIGTTIN | stop(*) |
84 * | SIGTTOU | stop(*) |
86 * | SIGXCPU | coredump |
87 * | SIGXFSZ | coredump |
88 * | SIGVTALRM | terminate |
89 * | SIGPROF | terminate |
90 * | SIGPOLL/SIGIO | terminate |
91 * | SIGSYS/SIGUNUSED | coredump |
92 * | SIGSTKFLT | terminate |
93 * | SIGWINCH | ignore |
94 * | SIGPWR | terminate |
95 * | SIGRTMIN-SIGRTMAX | terminate |
96 * +--------------------+------------------+
97 * | non-POSIX signal | default action |
98 * +--------------------+------------------+
99 * | SIGEMT | coredump |
100 * +--------------------+------------------+
102 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
103 * (*) Special job control effects:
104 * When SIGCONT is sent, it resumes the process (all threads in the group)
105 * from TASK_STOPPED state and also clears any pending/queued stop signals
106 * (any of those marked with "stop(*)"). This happens regardless of blocking,
107 * catching, or ignoring SIGCONT. When any stop signal is sent, it clears
108 * any pending/queued SIGCONT signals; this happens regardless of blocking,
109 * catching, or ignored the stop signal, though (except for SIGSTOP) the
110 * default action of stopping the process may happen later or never.
114 #define M_SIGEMT M(SIGEMT)
119 #if SIGRTMIN > BITS_PER_LONG
120 #define M(sig) (1ULL << ((sig)-1))
122 #define M(sig) (1UL << ((sig)-1))
124 #define T(sig, mask) (M(sig) & (mask))
126 #define SIG_KERNEL_ONLY_MASK (\
127 M(SIGKILL) | M(SIGSTOP) )
129 #define SIG_KERNEL_STOP_MASK (\
130 M(SIGSTOP) | M(SIGTSTP) | M(SIGTTIN) | M(SIGTTOU) )
132 #define SIG_KERNEL_COREDUMP_MASK (\
133 M(SIGQUIT) | M(SIGILL) | M(SIGTRAP) | M(SIGABRT) | \
134 M(SIGFPE) | M(SIGSEGV) | M(SIGBUS) | M(SIGSYS) | \
135 M(SIGXCPU) | M(SIGXFSZ) | M_SIGEMT )
137 #define SIG_KERNEL_IGNORE_MASK (\
138 M(SIGCONT) | M(SIGCHLD) | M(SIGWINCH) | M(SIGURG) )
140 #define sig_kernel_only(sig) \
141 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_ONLY_MASK))
142 #define sig_kernel_coredump(sig) \
143 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_COREDUMP_MASK))
144 #define sig_kernel_ignore(sig) \
145 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_IGNORE_MASK))
146 #define sig_kernel_stop(sig) \
147 (((sig) < SIGRTMIN) && T(sig, SIG_KERNEL_STOP_MASK))
149 #define sig_user_defined(t, signr) \
150 (((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) && \
151 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))
153 #define sig_fatal(t, signr) \
154 (!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
155 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
157 static int sig_ignored(struct task_struct *t, int sig)
159 void __user * handler;
162 * Tracers always want to know about signals..
164 if (t->ptrace & PT_PTRACED)
168 * Blocked signals are never ignored, since the
169 * signal handler may change by the time it is
172 if (sigismember(&t->blocked, sig))
175 /* Is it explicitly or implicitly ignored? */
176 handler = t->sighand->action[sig-1].sa.sa_handler;
177 return handler == SIG_IGN ||
178 (handler == SIG_DFL && sig_kernel_ignore(sig));
182 * Re-calculate pending state from the set of locally pending
183 * signals, globally pending signals, and blocked signals.
185 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
190 switch (_NSIG_WORDS) {
192 for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
193 ready |= signal->sig[i] &~ blocked->sig[i];
196 case 4: ready = signal->sig[3] &~ blocked->sig[3];
197 ready |= signal->sig[2] &~ blocked->sig[2];
198 ready |= signal->sig[1] &~ blocked->sig[1];
199 ready |= signal->sig[0] &~ blocked->sig[0];
202 case 2: ready = signal->sig[1] &~ blocked->sig[1];
203 ready |= signal->sig[0] &~ blocked->sig[0];
206 case 1: ready = signal->sig[0] &~ blocked->sig[0];
211 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
213 fastcall void recalc_sigpending_tsk(struct task_struct *t)
215 if (t->signal->group_stop_count > 0 ||
217 PENDING(&t->pending, &t->blocked) ||
218 PENDING(&t->signal->shared_pending, &t->blocked))
219 set_tsk_thread_flag(t, TIF_SIGPENDING);
221 clear_tsk_thread_flag(t, TIF_SIGPENDING);
224 void recalc_sigpending(void)
226 recalc_sigpending_tsk(current);
229 /* Given the mask, find the first available signal that should be serviced. */
232 next_signal(struct sigpending *pending, sigset_t *mask)
234 unsigned long i, *s, *m, x;
237 s = pending->signal.sig;
239 switch (_NSIG_WORDS) {
241 for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
242 if ((x = *s &~ *m) != 0) {
243 sig = ffz(~x) + i*_NSIG_BPW + 1;
248 case 2: if ((x = s[0] &~ m[0]) != 0)
250 else if ((x = s[1] &~ m[1]) != 0)
257 case 1: if ((x = *s &~ *m) != 0)
265 static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
268 struct sigqueue *q = NULL;
270 atomic_inc(&t->user->sigpending);
271 if (override_rlimit ||
272 atomic_read(&t->user->sigpending) <=
273 t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
274 q = kmem_cache_alloc(sigqueue_cachep, flags);
275 if (unlikely(q == NULL)) {
276 atomic_dec(&t->user->sigpending);
278 INIT_LIST_HEAD(&q->list);
280 q->user = get_uid(t->user);
285 static inline void __sigqueue_free(struct sigqueue *q)
287 if (q->flags & SIGQUEUE_PREALLOC)
289 atomic_dec(&q->user->sigpending);
291 kmem_cache_free(sigqueue_cachep, q);
294 static void flush_sigqueue(struct sigpending *queue)
298 sigemptyset(&queue->signal);
299 while (!list_empty(&queue->list)) {
300 q = list_entry(queue->list.next, struct sigqueue , list);
301 list_del_init(&q->list);
307 * Flush all pending signals for a task.
311 flush_signals(struct task_struct *t)
315 spin_lock_irqsave(&t->sighand->siglock, flags);
316 clear_tsk_thread_flag(t,TIF_SIGPENDING);
317 flush_sigqueue(&t->pending);
318 flush_sigqueue(&t->signal->shared_pending);
319 spin_unlock_irqrestore(&t->sighand->siglock, flags);
323 * This function expects the tasklist_lock write-locked.
325 void __exit_sighand(struct task_struct *tsk)
327 struct sighand_struct * sighand = tsk->sighand;
329 /* Ok, we're done with the signal handlers */
331 if (atomic_dec_and_test(&sighand->count))
332 sighand_free(sighand);
335 void exit_sighand(struct task_struct *tsk)
337 write_lock_irq(&tasklist_lock);
339 if (tsk->sighand != NULL) {
340 struct sighand_struct *sighand = rcu_dereference(tsk->sighand);
341 spin_lock(&sighand->siglock);
343 spin_unlock(&sighand->siglock);
346 write_unlock_irq(&tasklist_lock);
350 * This function expects the tasklist_lock write-locked.
352 void __exit_signal(struct task_struct *tsk)
354 struct signal_struct * sig = tsk->signal;
355 struct sighand_struct * sighand;
359 if (!atomic_read(&sig->count))
362 sighand = rcu_dereference(tsk->sighand);
363 spin_lock(&sighand->siglock);
364 posix_cpu_timers_exit(tsk);
365 if (atomic_dec_and_test(&sig->count)) {
366 posix_cpu_timers_exit_group(tsk);
367 if (tsk == sig->curr_target)
368 sig->curr_target = next_thread(tsk);
371 spin_unlock(&sighand->siglock);
372 flush_sigqueue(&sig->shared_pending);
375 * If there is any task waiting for the group exit
378 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
379 wake_up_process(sig->group_exit_task);
380 sig->group_exit_task = NULL;
382 if (tsk == sig->curr_target)
383 sig->curr_target = next_thread(tsk);
386 * Accumulate here the counters for all threads but the
387 * group leader as they die, so they can be added into
388 * the process-wide totals when those are taken.
389 * The group leader stays around as a zombie as long
390 * as there are other threads. When it gets reaped,
391 * the exit.c code will add its counts into these totals.
392 * We won't ever get here for the group leader, since it
393 * will have been the last reference on the signal_struct.
395 sig->utime = cputime_add(sig->utime, tsk->utime);
396 sig->stime = cputime_add(sig->stime, tsk->stime);
397 sig->min_flt += tsk->min_flt;
398 sig->maj_flt += tsk->maj_flt;
399 sig->nvcsw += tsk->nvcsw;
400 sig->nivcsw += tsk->nivcsw;
401 sig->sched_time += tsk->sched_time;
403 spin_unlock(&sighand->siglock);
404 sig = NULL; /* Marker for below. */
407 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
408 flush_sigqueue(&tsk->pending);
411 * We are cleaning up the signal_struct here.
413 exit_thread_group_keys(sig);
414 kmem_cache_free(signal_cachep, sig);
418 void exit_signal(struct task_struct *tsk)
420 atomic_dec(&tsk->signal->live);
422 write_lock_irq(&tasklist_lock);
424 write_unlock_irq(&tasklist_lock);
428 * Flush all handlers for a task.
432 flush_signal_handlers(struct task_struct *t, int force_default)
435 struct k_sigaction *ka = &t->sighand->action[0];
436 for (i = _NSIG ; i != 0 ; i--) {
437 if (force_default || ka->sa.sa_handler != SIG_IGN)
438 ka->sa.sa_handler = SIG_DFL;
440 sigemptyset(&ka->sa.sa_mask);
446 /* Notify the system that a driver wants to block all signals for this
447 * process, and wants to be notified if any signals at all were to be
448 * sent/acted upon. If the notifier routine returns non-zero, then the
449 * signal will be acted upon after all. If the notifier routine returns 0,
450 * then then signal will be blocked. Only one block per process is
451 * allowed. priv is a pointer to private data that the notifier routine
452 * can use to determine if the signal should be blocked or not. */
455 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
459 spin_lock_irqsave(¤t->sighand->siglock, flags);
460 current->notifier_mask = mask;
461 current->notifier_data = priv;
462 current->notifier = notifier;
463 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
466 /* Notify the system that blocking has ended. */
469 unblock_all_signals(void)
473 spin_lock_irqsave(¤t->sighand->siglock, flags);
474 current->notifier = NULL;
475 current->notifier_data = NULL;
477 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
480 static inline int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
482 struct sigqueue *q, *first = NULL;
483 int still_pending = 0;
485 if (unlikely(!sigismember(&list->signal, sig)))
489 * Collect the siginfo appropriate to this signal. Check if
490 * there is another siginfo for the same signal.
492 list_for_each_entry(q, &list->list, list) {
493 if (q->info.si_signo == sig) {
502 list_del_init(&first->list);
503 copy_siginfo(info, &first->info);
504 __sigqueue_free(first);
506 sigdelset(&list->signal, sig);
509 /* Ok, it wasn't in the queue. This must be
510 a fast-pathed signal or we must have been
511 out of queue space. So zero out the info.
513 sigdelset(&list->signal, sig);
514 info->si_signo = sig;
523 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
528 sig = next_signal(pending, mask);
530 if (current->notifier) {
531 if (sigismember(current->notifier_mask, sig)) {
532 if (!(current->notifier)(current->notifier_data)) {
533 clear_thread_flag(TIF_SIGPENDING);
539 if (!collect_signal(sig, pending, info))
549 * Dequeue a signal and return the element to the caller, which is
550 * expected to free it.
552 * All callers have to hold the siglock.
554 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
556 int signr = __dequeue_signal(&tsk->pending, mask, info);
558 signr = __dequeue_signal(&tsk->signal->shared_pending,
560 if (signr && unlikely(sig_kernel_stop(signr))) {
562 * Set a marker that we have dequeued a stop signal. Our
563 * caller might release the siglock and then the pending
564 * stop signal it is about to process is no longer in the
565 * pending bitmasks, but must still be cleared by a SIGCONT
566 * (and overruled by a SIGKILL). So those cases clear this
567 * shared flag after we've set it. Note that this flag may
568 * remain set after the signal we return is ignored or
569 * handled. That doesn't matter because its only purpose
570 * is to alert stop-signal processing code when another
571 * processor has come along and cleared the flag.
573 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
574 tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
577 ((info->si_code & __SI_MASK) == __SI_TIMER) &&
578 info->si_sys_private){
580 * Release the siglock to ensure proper locking order
581 * of timer locks outside of siglocks. Note, we leave
582 * irqs disabled here, since the posix-timers code is
583 * about to disable them again anyway.
585 spin_unlock(&tsk->sighand->siglock);
586 do_schedule_next_timer(info);
587 spin_lock(&tsk->sighand->siglock);
593 * Tell a process that it has a new active signal..
595 * NOTE! we rely on the previous spin_lock to
596 * lock interrupts for us! We can only be called with
597 * "siglock" held, and the local interrupt must
598 * have been disabled when that got acquired!
600 * No need to set need_resched since signal event passing
601 * goes through ->blocked
603 void signal_wake_up(struct task_struct *t, int resume)
607 set_tsk_thread_flag(t, TIF_SIGPENDING);
610 * For SIGKILL, we want to wake it up in the stopped/traced case.
611 * We don't check t->state here because there is a race with it
612 * executing another processor and just now entering stopped state.
613 * By using wake_up_state, we ensure the process will wake up and
614 * handle its death signal.
616 mask = TASK_INTERRUPTIBLE;
618 mask |= TASK_STOPPED | TASK_TRACED;
619 if (!wake_up_state(t, mask))
624 * Remove signals in mask from the pending set and queue.
625 * Returns 1 if any signals were found.
627 * All callers must be holding the siglock.
629 static int rm_from_queue(unsigned long mask, struct sigpending *s)
631 struct sigqueue *q, *n;
633 if (!sigtestsetmask(&s->signal, mask))
636 sigdelsetmask(&s->signal, mask);
637 list_for_each_entry_safe(q, n, &s->list, list) {
638 if (q->info.si_signo < SIGRTMIN &&
639 (mask & sigmask(q->info.si_signo))) {
640 list_del_init(&q->list);
648 * Bad permissions for sending the signal
650 static int check_kill_permission(int sig, struct siginfo *info,
651 struct task_struct *t)
654 if (!valid_signal(sig))
657 if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
658 && ((sig != SIGCONT) ||
659 (current->signal->session != t->signal->session))
660 && (current->euid ^ t->suid) && (current->euid ^ t->uid)
661 && (current->uid ^ t->suid) && (current->uid ^ t->uid)
662 && !capable(CAP_KILL))
665 error = security_task_kill(t, info, sig);
667 audit_signal_info(sig, t); /* Let audit system see the signal */
672 static void do_notify_parent_cldstop(struct task_struct *tsk,
677 * Handle magic process-wide effects of stop/continue signals.
678 * Unlike the signal actions, these happen immediately at signal-generation
679 * time regardless of blocking, ignoring, or handling. This does the
680 * actual continuing for SIGCONT, but not the actual stopping for stop
681 * signals. The process stop is done as a signal action for SIG_DFL.
683 static void handle_stop_signal(int sig, struct task_struct *p)
685 struct task_struct *t;
687 if (p->signal->flags & SIGNAL_GROUP_EXIT)
689 * The process is in the middle of dying already.
693 if (sig_kernel_stop(sig)) {
695 * This is a stop signal. Remove SIGCONT from all queues.
697 rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
700 rm_from_queue(sigmask(SIGCONT), &t->pending);
703 } else if (sig == SIGCONT) {
705 * Remove all stop signals from all queues,
706 * and wake all threads.
708 if (unlikely(p->signal->group_stop_count > 0)) {
710 * There was a group stop in progress. We'll
711 * pretend it finished before we got here. We are
712 * obliged to report it to the parent: if the
713 * SIGSTOP happened "after" this SIGCONT, then it
714 * would have cleared this pending SIGCONT. If it
715 * happened "before" this SIGCONT, then the parent
716 * got the SIGCHLD about the stop finishing before
717 * the continue happened. We do the notification
718 * now, and it's as if the stop had finished and
719 * the SIGCHLD was pending on entry to this kill.
721 p->signal->group_stop_count = 0;
722 p->signal->flags = SIGNAL_STOP_CONTINUED;
723 spin_unlock(&p->sighand->siglock);
724 do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_STOPPED);
725 spin_lock(&p->sighand->siglock);
727 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
731 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
734 * If there is a handler for SIGCONT, we must make
735 * sure that no thread returns to user mode before
736 * we post the signal, in case it was the only
737 * thread eligible to run the signal handler--then
738 * it must not do anything between resuming and
739 * running the handler. With the TIF_SIGPENDING
740 * flag set, the thread will pause and acquire the
741 * siglock that we hold now and until we've queued
742 * the pending signal.
744 * Wake up the stopped thread _after_ setting
747 state = TASK_STOPPED;
748 if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
749 set_tsk_thread_flag(t, TIF_SIGPENDING);
750 state |= TASK_INTERRUPTIBLE;
752 wake_up_state(t, state);
757 if (p->signal->flags & SIGNAL_STOP_STOPPED) {
759 * We were in fact stopped, and are now continued.
760 * Notify the parent with CLD_CONTINUED.
762 p->signal->flags = SIGNAL_STOP_CONTINUED;
763 p->signal->group_exit_code = 0;
764 spin_unlock(&p->sighand->siglock);
765 do_notify_parent_cldstop(p, (p->ptrace & PT_PTRACED), CLD_CONTINUED);
766 spin_lock(&p->sighand->siglock);
769 * We are not stopped, but there could be a stop
770 * signal in the middle of being processed after
771 * being removed from the queue. Clear that too.
773 p->signal->flags = 0;
775 } else if (sig == SIGKILL) {
777 * Make sure that any pending stop signal already dequeued
778 * is undone by the wakeup for SIGKILL.
780 p->signal->flags = 0;
784 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
785 struct sigpending *signals)
787 struct sigqueue * q = NULL;
791 * fast-pathed signals for kernel-internal things like SIGSTOP
794 if (info == SEND_SIG_FORCED)
797 /* Real-time signals must be queued if sent by sigqueue, or
798 some other real-time mechanism. It is implementation
799 defined whether kill() does so. We attempt to do so, on
800 the principle of least surprise, but since kill is not
801 allowed to fail with EAGAIN when low on memory we just
802 make sure at least one signal gets delivered and don't
803 pass on the info struct. */
805 q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
806 (is_si_special(info) ||
807 info->si_code >= 0)));
809 list_add_tail(&q->list, &signals->list);
810 switch ((unsigned long) info) {
811 case (unsigned long) SEND_SIG_NOINFO:
812 q->info.si_signo = sig;
813 q->info.si_errno = 0;
814 q->info.si_code = SI_USER;
815 q->info.si_pid = current->pid;
816 q->info.si_uid = current->uid;
818 case (unsigned long) SEND_SIG_PRIV:
819 q->info.si_signo = sig;
820 q->info.si_errno = 0;
821 q->info.si_code = SI_KERNEL;
826 copy_siginfo(&q->info, info);
829 } else if (!is_si_special(info)) {
830 if (sig >= SIGRTMIN && info->si_code != SI_USER)
832 * Queue overflow, abort. We may abort if the signal was rt
833 * and sent by user using something other than kill().
839 sigaddset(&signals->signal, sig);
843 #define LEGACY_QUEUE(sigptr, sig) \
844 (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
848 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
852 if (!irqs_disabled())
854 assert_spin_locked(&t->sighand->siglock);
856 /* Short-circuit ignored signals. */
857 if (sig_ignored(t, sig))
860 /* Support queueing exactly one non-rt signal, so that we
861 can get more detailed information about the cause of
863 if (LEGACY_QUEUE(&t->pending, sig))
866 ret = send_signal(sig, info, t, &t->pending);
867 if (!ret && !sigismember(&t->blocked, sig))
868 signal_wake_up(t, sig == SIGKILL);
874 * Force a signal that the process can't ignore: if necessary
875 * we unblock the signal and change any SIG_IGN to SIG_DFL.
879 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
881 unsigned long int flags;
884 spin_lock_irqsave(&t->sighand->siglock, flags);
885 if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) {
886 t->sighand->action[sig-1].sa.sa_handler = SIG_DFL;
888 if (sigismember(&t->blocked, sig)) {
889 sigdelset(&t->blocked, sig);
891 recalc_sigpending_tsk(t);
892 ret = specific_send_sig_info(sig, info, t);
893 spin_unlock_irqrestore(&t->sighand->siglock, flags);
899 force_sig_specific(int sig, struct task_struct *t)
901 force_sig_info(sig, SEND_SIG_FORCED, t);
905 * Test if P wants to take SIG. After we've checked all threads with this,
906 * it's equivalent to finding no threads not blocking SIG. Any threads not
907 * blocking SIG were ruled out because they are not running and already
908 * have pending signals. Such threads will dequeue from the shared queue
909 * as soon as they're available, so putting the signal on the shared queue
910 * will be equivalent to sending it to one such thread.
912 static inline int wants_signal(int sig, struct task_struct *p)
914 if (sigismember(&p->blocked, sig))
916 if (p->flags & PF_EXITING)
920 if (p->state & (TASK_STOPPED | TASK_TRACED))
922 return task_curr(p) || !signal_pending(p);
926 __group_complete_signal(int sig, struct task_struct *p)
928 struct task_struct *t;
931 * Now find a thread we can wake up to take the signal off the queue.
933 * If the main thread wants the signal, it gets first crack.
934 * Probably the least surprising to the average bear.
936 if (wants_signal(sig, p))
938 else if (thread_group_empty(p))
940 * There is just one thread and it does not need to be woken.
941 * It will dequeue unblocked signals before it runs again.
946 * Otherwise try to find a suitable thread.
948 t = p->signal->curr_target;
950 /* restart balancing at this thread */
951 t = p->signal->curr_target = p;
952 BUG_ON(t->tgid != p->tgid);
954 while (!wants_signal(sig, t)) {
956 if (t == p->signal->curr_target)
958 * No thread needs to be woken.
959 * Any eligible threads will see
960 * the signal in the queue soon.
964 p->signal->curr_target = t;
968 * Found a killable thread. If the signal will be fatal,
969 * then start taking the whole group down immediately.
971 if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
972 !sigismember(&t->real_blocked, sig) &&
973 (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
975 * This signal will be fatal to the whole group.
977 if (!sig_kernel_coredump(sig)) {
979 * Start a group exit and wake everybody up.
980 * This way we don't have other threads
981 * running and doing things after a slower
982 * thread has the fatal signal pending.
984 p->signal->flags = SIGNAL_GROUP_EXIT;
985 p->signal->group_exit_code = sig;
986 p->signal->group_stop_count = 0;
989 sigaddset(&t->pending.signal, SIGKILL);
990 signal_wake_up(t, 1);
997 * There will be a core dump. We make all threads other
998 * than the chosen one go into a group stop so that nothing
999 * happens until it gets scheduled, takes the signal off
1000 * the shared queue, and does the core dump. This is a
1001 * little more complicated than strictly necessary, but it
1002 * keeps the signal state that winds up in the core dump
1003 * unchanged from the death state, e.g. which thread had
1004 * the core-dump signal unblocked.
1006 rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
1007 rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
1008 p->signal->group_stop_count = 0;
1009 p->signal->group_exit_task = t;
1012 p->signal->group_stop_count++;
1013 signal_wake_up(t, 0);
1016 wake_up_process(p->signal->group_exit_task);
1021 * The signal is already in the shared-pending queue.
1022 * Tell the chosen thread to wake up and dequeue it.
1024 signal_wake_up(t, sig == SIGKILL);
1029 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1033 assert_spin_locked(&p->sighand->siglock);
1034 handle_stop_signal(sig, p);
1036 /* Short-circuit ignored signals. */
1037 if (sig_ignored(p, sig))
1040 if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
1041 /* This is a non-RT signal and we already have one queued. */
1045 * Put this signal on the shared-pending queue, or fail with EAGAIN.
1046 * We always use the shared queue for process-wide signals,
1047 * to avoid several races.
1049 ret = send_signal(sig, info, p, &p->signal->shared_pending);
1053 __group_complete_signal(sig, p);
1058 * Nuke all other threads in the group.
1060 void zap_other_threads(struct task_struct *p)
1062 struct task_struct *t;
1064 p->signal->flags = SIGNAL_GROUP_EXIT;
1065 p->signal->group_stop_count = 0;
1067 if (thread_group_empty(p))
1070 for (t = next_thread(p); t != p; t = next_thread(t)) {
1072 * Don't bother with already dead threads
1078 * We don't want to notify the parent, since we are
1079 * killed as part of a thread group due to another
1080 * thread doing an execve() or similar. So set the
1081 * exit signal to -1 to allow immediate reaping of
1082 * the process. But don't detach the thread group
1085 if (t != p->group_leader)
1086 t->exit_signal = -1;
1088 /* SIGKILL will be handled before any pending SIGSTOP */
1089 sigaddset(&t->pending.signal, SIGKILL);
1090 signal_wake_up(t, 1);
1095 * Must be called under rcu_read_lock() or with tasklist_lock read-held.
1097 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1099 unsigned long flags;
1100 struct sighand_struct *sp;
1104 ret = check_kill_permission(sig, info, p);
1105 if (!ret && sig && (sp = p->sighand)) {
1106 if (!get_task_struct_rcu(p))
1108 spin_lock_irqsave(&sp->siglock, flags);
1109 if (p->sighand != sp) {
1110 spin_unlock_irqrestore(&sp->siglock, flags);
1114 ret = __group_send_sig_info(sig, info, p);
1115 spin_unlock_irqrestore(&sp->siglock, flags);
1123 * kill_pg_info() sends a signal to a process group: this is what the tty
1124 * control characters do (^C, ^Z etc)
1127 int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1129 struct task_struct *p = NULL;
1130 int retval, success;
1137 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
1138 int err = group_send_sig_info(sig, info, p);
1141 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
1142 return success ? 0 : retval;
1146 kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
1150 read_lock(&tasklist_lock);
1151 retval = __kill_pg_info(sig, info, pgrp);
1152 read_unlock(&tasklist_lock);
1158 kill_proc_info(int sig, struct siginfo *info, pid_t pid)
1161 int acquired_tasklist_lock = 0;
1162 struct task_struct *p;
1165 if (unlikely(sig_kernel_stop(sig) || sig == SIGCONT)) {
1166 read_lock(&tasklist_lock);
1167 acquired_tasklist_lock = 1;
1169 p = find_task_by_pid(pid);
1172 error = group_send_sig_info(sig, info, p);
1173 if (unlikely(acquired_tasklist_lock))
1174 read_unlock(&tasklist_lock);
1179 /* like kill_proc_info(), but doesn't use uid/euid of "current" */
1180 int kill_proc_info_as_uid(int sig, struct siginfo *info, pid_t pid,
1181 uid_t uid, uid_t euid)
1184 struct task_struct *p;
1186 if (!valid_signal(sig))
1189 read_lock(&tasklist_lock);
1190 p = find_task_by_pid(pid);
1195 if ((!info || ((unsigned long)info != 1 &&
1196 (unsigned long)info != 2 && SI_FROMUSER(info)))
1197 && (euid != p->suid) && (euid != p->uid)
1198 && (uid != p->suid) && (uid != p->uid)) {
1202 if (sig && p->sighand) {
1203 unsigned long flags;
1204 spin_lock_irqsave(&p->sighand->siglock, flags);
1205 ret = __group_send_sig_info(sig, info, p);
1206 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1209 read_unlock(&tasklist_lock);
1212 EXPORT_SYMBOL_GPL(kill_proc_info_as_uid);
1215 * kill_something_info() interprets pid in interesting ways just like kill(2).
1217 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
1218 * is probably wrong. Should make it like BSD or SYSV.
1221 static int kill_something_info(int sig, struct siginfo *info, int pid)
1224 return kill_pg_info(sig, info, process_group(current));
1225 } else if (pid == -1) {
1226 int retval = 0, count = 0;
1227 struct task_struct * p;
1229 read_lock(&tasklist_lock);
1230 for_each_process(p) {
1231 if (p->pid > 1 && p->tgid != current->tgid) {
1232 int err = group_send_sig_info(sig, info, p);
1238 read_unlock(&tasklist_lock);
1239 return count ? retval : -ESRCH;
1240 } else if (pid < 0) {
1241 return kill_pg_info(sig, info, -pid);
1243 return kill_proc_info(sig, info, pid);
1248 * These are for backward compatibility with the rest of the kernel source.
1252 * These two are the most common entry points. They send a signal
1253 * just to the specific thread.
1256 send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1259 unsigned long flags;
1262 * Make sure legacy kernel users don't send in bad values
1263 * (normal paths check this in check_kill_permission).
1265 if (!valid_signal(sig))
1269 * We need the tasklist lock even for the specific
1270 * thread case (when we don't need to follow the group
1271 * lists) in order to avoid races with "p->sighand"
1272 * going away or changing from under us.
1274 read_lock(&tasklist_lock);
1275 spin_lock_irqsave(&p->sighand->siglock, flags);
1276 ret = specific_send_sig_info(sig, info, p);
1277 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1278 read_unlock(&tasklist_lock);
1282 #define __si_special(priv) \
1283 ((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
1286 send_sig(int sig, struct task_struct *p, int priv)
1288 return send_sig_info(sig, __si_special(priv), p);
1292 * This is the entry point for "process-wide" signals.
1293 * They will go to an appropriate thread in the thread group.
1296 send_group_sig_info(int sig, struct siginfo *info, struct task_struct *p)
1299 read_lock(&tasklist_lock);
1300 ret = group_send_sig_info(sig, info, p);
1301 read_unlock(&tasklist_lock);
1306 force_sig(int sig, struct task_struct *p)
1308 force_sig_info(sig, SEND_SIG_PRIV, p);
1312 * When things go south during signal handling, we
1313 * will force a SIGSEGV. And if the signal that caused
1314 * the problem was already a SIGSEGV, we'll want to
1315 * make sure we don't even try to deliver the signal..
1318 force_sigsegv(int sig, struct task_struct *p)
1320 if (sig == SIGSEGV) {
1321 unsigned long flags;
1322 spin_lock_irqsave(&p->sighand->siglock, flags);
1323 p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
1324 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1326 force_sig(SIGSEGV, p);
1331 kill_pg(pid_t pgrp, int sig, int priv)
1333 return kill_pg_info(sig, __si_special(priv), pgrp);
1337 kill_proc(pid_t pid, int sig, int priv)
1339 return kill_proc_info(sig, __si_special(priv), pid);
1343 * These functions support sending signals using preallocated sigqueue
1344 * structures. This is needed "because realtime applications cannot
1345 * afford to lose notifications of asynchronous events, like timer
1346 * expirations or I/O completions". In the case of Posix Timers
1347 * we allocate the sigqueue structure from the timer_create. If this
1348 * allocation fails we are able to report the failure to the application
1349 * with an EAGAIN error.
1352 struct sigqueue *sigqueue_alloc(void)
1356 if ((q = __sigqueue_alloc(current, GFP_KERNEL, 0)))
1357 q->flags |= SIGQUEUE_PREALLOC;
1361 void sigqueue_free(struct sigqueue *q)
1363 unsigned long flags;
1364 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1366 * If the signal is still pending remove it from the
1369 if (unlikely(!list_empty(&q->list))) {
1370 spinlock_t *lock = ¤t->sighand->siglock;
1371 read_lock(&tasklist_lock);
1372 spin_lock_irqsave(lock, flags);
1373 if (!list_empty(&q->list))
1374 list_del_init(&q->list);
1375 spin_unlock_irqrestore(lock, flags);
1376 read_unlock(&tasklist_lock);
1378 q->flags &= ~SIGQUEUE_PREALLOC;
1383 send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1385 unsigned long flags;
1387 struct sighand_struct *sh;
1389 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1392 * The rcu based delayed sighand destroy makes it possible to
1393 * run this without tasklist lock held. The task struct itself
1394 * cannot go away as create_timer did get_task_struct().
1396 * We return -1, when the task is marked exiting, so
1397 * posix_timer_event can redirect it to the group leader
1401 if (unlikely(p->flags & PF_EXITING)) {
1407 sh = rcu_dereference(p->sighand);
1409 spin_lock_irqsave(&sh->siglock, flags);
1410 if (p->sighand != sh) {
1411 /* We raced with exec() in a multithreaded process... */
1412 spin_unlock_irqrestore(&sh->siglock, flags);
1417 * We do the check here again to handle the following scenario:
1422 * interrupt exit code running
1424 * lock sighand->siglock
1425 * unlock sighand->siglock
1427 * add(tsk->pending) flush_sigqueue(tsk->pending)
1431 if (unlikely(p->flags & PF_EXITING)) {
1436 if (unlikely(!list_empty(&q->list))) {
1438 * If an SI_TIMER entry is already queue just increment
1439 * the overrun count.
1441 if (q->info.si_code != SI_TIMER)
1443 q->info.si_overrun++;
1446 /* Short-circuit ignored signals. */
1447 if (sig_ignored(p, sig)) {
1452 list_add_tail(&q->list, &p->pending.list);
1453 sigaddset(&p->pending.signal, sig);
1454 if (!sigismember(&p->blocked, sig))
1455 signal_wake_up(p, sig == SIGKILL);
1458 spin_unlock_irqrestore(&sh->siglock, flags);
1466 send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
1468 unsigned long flags;
1471 BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
1473 read_lock(&tasklist_lock);
1474 /* Since it_lock is held, p->sighand cannot be NULL. */
1475 spin_lock_irqsave(&p->sighand->siglock, flags);
1476 handle_stop_signal(sig, p);
1478 /* Short-circuit ignored signals. */
1479 if (sig_ignored(p, sig)) {
1484 if (unlikely(!list_empty(&q->list))) {
1486 * If an SI_TIMER entry is already queue just increment
1487 * the overrun count. Other uses should not try to
1488 * send the signal multiple times.
1490 if (q->info.si_code != SI_TIMER)
1492 q->info.si_overrun++;
1497 * Put this signal on the shared-pending queue.
1498 * We always use the shared queue for process-wide signals,
1499 * to avoid several races.
1501 list_add_tail(&q->list, &p->signal->shared_pending.list);
1502 sigaddset(&p->signal->shared_pending.signal, sig);
1504 __group_complete_signal(sig, p);
1506 spin_unlock_irqrestore(&p->sighand->siglock, flags);
1507 read_unlock(&tasklist_lock);
1512 * Wake up any threads in the parent blocked in wait* syscalls.
1514 static inline void __wake_up_parent(struct task_struct *p,
1515 struct task_struct *parent)
1517 wake_up_interruptible_sync(&parent->signal->wait_chldexit);
1521 * Let a parent know about the death of a child.
1522 * For a stopped/continued status change, use do_notify_parent_cldstop instead.
1525 void do_notify_parent(struct task_struct *tsk, int sig)
1527 struct siginfo info;
1528 unsigned long flags;
1529 struct sighand_struct *psig;
1533 /* do_notify_parent_cldstop should have been called instead. */
1534 BUG_ON(tsk->state & (TASK_STOPPED|TASK_TRACED));
1536 BUG_ON(!tsk->ptrace &&
1537 (tsk->group_leader != tsk || !thread_group_empty(tsk)));
1539 info.si_signo = sig;
1541 info.si_pid = tsk->pid;
1542 info.si_uid = tsk->uid;
1544 /* FIXME: find out whether or not this is supposed to be c*time. */
1545 info.si_utime = cputime_to_jiffies(cputime_add(tsk->utime,
1546 tsk->signal->utime));
1547 info.si_stime = cputime_to_jiffies(cputime_add(tsk->stime,
1548 tsk->signal->stime));
1550 info.si_status = tsk->exit_code & 0x7f;
1551 if (tsk->exit_code & 0x80)
1552 info.si_code = CLD_DUMPED;
1553 else if (tsk->exit_code & 0x7f)
1554 info.si_code = CLD_KILLED;
1556 info.si_code = CLD_EXITED;
1557 info.si_status = tsk->exit_code >> 8;
1560 psig = tsk->parent->sighand;
1561 spin_lock_irqsave(&psig->siglock, flags);
1562 if (!tsk->ptrace && sig == SIGCHLD &&
1563 (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
1564 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
1566 * We are exiting and our parent doesn't care. POSIX.1
1567 * defines special semantics for setting SIGCHLD to SIG_IGN
1568 * or setting the SA_NOCLDWAIT flag: we should be reaped
1569 * automatically and not left for our parent's wait4 call.
1570 * Rather than having the parent do it as a magic kind of
1571 * signal handler, we just set this to tell do_exit that we
1572 * can be cleaned up without becoming a zombie. Note that
1573 * we still call __wake_up_parent in this case, because a
1574 * blocked sys_wait4 might now return -ECHILD.
1576 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
1577 * is implementation-defined: we do (if you don't want
1578 * it, just use SIG_IGN instead).
1580 tsk->exit_signal = -1;
1581 if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
1584 if (valid_signal(sig) && sig > 0)
1585 __group_send_sig_info(sig, &info, tsk->parent);
1586 __wake_up_parent(tsk, tsk->parent);
1587 spin_unlock_irqrestore(&psig->siglock, flags);
1590 static void do_notify_parent_cldstop(struct task_struct *tsk, int to_self, int why)
1592 struct siginfo info;
1593 unsigned long flags;
1594 struct task_struct *parent;
1595 struct sighand_struct *sighand;
1598 parent = tsk->parent;
1600 tsk = tsk->group_leader;
1601 parent = tsk->real_parent;
1604 info.si_signo = SIGCHLD;
1606 info.si_pid = tsk->pid;
1607 info.si_uid = tsk->uid;
1609 /* FIXME: find out whether or not this is supposed to be c*time. */
1610 info.si_utime = cputime_to_jiffies(tsk->utime);
1611 info.si_stime = cputime_to_jiffies(tsk->stime);
1616 info.si_status = SIGCONT;
1619 info.si_status = tsk->signal->group_exit_code & 0x7f;
1622 info.si_status = tsk->exit_code & 0x7f;
1628 sighand = parent->sighand;
1629 spin_lock_irqsave(&sighand->siglock, flags);
1630 if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
1631 !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
1632 __group_send_sig_info(SIGCHLD, &info, parent);
1634 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
1636 __wake_up_parent(tsk, parent);
1637 spin_unlock_irqrestore(&sighand->siglock, flags);
1641 * This must be called with current->sighand->siglock held.
1643 * This should be the path for all ptrace stops.
1644 * We always set current->last_siginfo while stopped here.
1645 * That makes it a way to test a stopped process for
1646 * being ptrace-stopped vs being job-control-stopped.
1648 * If we actually decide not to stop at all because the tracer is gone,
1649 * we leave nostop_code in current->exit_code.
1651 static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
1654 * If there is a group stop in progress,
1655 * we must participate in the bookkeeping.
1657 if (current->signal->group_stop_count > 0)
1658 --current->signal->group_stop_count;
1660 current->last_siginfo = info;
1661 current->exit_code = exit_code;
1663 /* Let the debugger run. */
1664 set_current_state(TASK_TRACED);
1665 spin_unlock_irq(¤t->sighand->siglock);
1666 read_lock(&tasklist_lock);
1667 if (likely(current->ptrace & PT_PTRACED) &&
1668 likely(current->parent != current->real_parent ||
1669 !(current->ptrace & PT_ATTACHED)) &&
1670 (likely(current->parent->signal != current->signal) ||
1671 !unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
1672 do_notify_parent_cldstop(current, 1, CLD_TRAPPED);
1673 read_unlock(&tasklist_lock);
1677 * By the time we got the lock, our tracer went away.
1680 read_unlock(&tasklist_lock);
1681 set_current_state(TASK_RUNNING);
1682 current->exit_code = nostop_code;
1686 * We are back. Now reacquire the siglock before touching
1687 * last_siginfo, so that we are sure to have synchronized with
1688 * any signal-sending on another CPU that wants to examine it.
1690 spin_lock_irq(¤t->sighand->siglock);
1691 current->last_siginfo = NULL;
1694 * Queued signals ignored us while we were stopped for tracing.
1695 * So check for any that we should take before resuming user mode.
1697 recalc_sigpending();
1700 void ptrace_notify(int exit_code)
1704 BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
1706 memset(&info, 0, sizeof info);
1707 info.si_signo = SIGTRAP;
1708 info.si_code = exit_code;
1709 info.si_pid = current->pid;
1710 info.si_uid = current->uid;
1712 /* Let the debugger run. */
1713 spin_lock_irq(¤t->sighand->siglock);
1714 ptrace_stop(exit_code, 0, &info);
1715 spin_unlock_irq(¤t->sighand->siglock);
1719 finish_stop(int stop_count)
1724 * If there are no other threads in the group, or if there is
1725 * a group stop in progress and we are the last to stop,
1726 * report to the parent. When ptraced, every thread reports itself.
1728 if (stop_count < 0 || (current->ptrace & PT_PTRACED))
1730 else if (stop_count == 0)
1735 read_lock(&tasklist_lock);
1736 do_notify_parent_cldstop(current, to_self, CLD_STOPPED);
1737 read_unlock(&tasklist_lock);
1742 * Now we don't run again until continued.
1744 current->exit_code = 0;
1748 * This performs the stopping for SIGSTOP and other stop signals.
1749 * We have to stop all threads in the thread group.
1750 * Returns nonzero if we've actually stopped and released the siglock.
1751 * Returns zero if we didn't stop and still hold the siglock.
1754 do_signal_stop(int signr)
1756 struct signal_struct *sig = current->signal;
1757 struct sighand_struct *sighand = current->sighand;
1758 int stop_count = -1;
1760 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
1763 if (sig->group_stop_count > 0) {
1765 * There is a group stop in progress. We don't need to
1766 * start another one.
1768 signr = sig->group_exit_code;
1769 stop_count = --sig->group_stop_count;
1770 current->exit_code = signr;
1771 set_current_state(TASK_STOPPED);
1772 if (stop_count == 0)
1773 sig->flags = SIGNAL_STOP_STOPPED;
1774 spin_unlock_irq(&sighand->siglock);
1776 else if (thread_group_empty(current)) {
1778 * Lock must be held through transition to stopped state.
1780 current->exit_code = current->signal->group_exit_code = signr;
1781 set_current_state(TASK_STOPPED);
1782 sig->flags = SIGNAL_STOP_STOPPED;
1783 spin_unlock_irq(&sighand->siglock);
1787 * There is no group stop already in progress.
1788 * We must initiate one now, but that requires
1789 * dropping siglock to get both the tasklist lock
1790 * and siglock again in the proper order. Note that
1791 * this allows an intervening SIGCONT to be posted.
1792 * We need to check for that and bail out if necessary.
1794 struct task_struct *t;
1796 spin_unlock_irq(&sighand->siglock);
1798 /* signals can be posted during this window */
1800 read_lock(&tasklist_lock);
1801 spin_lock_irq(&sighand->siglock);
1803 if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
1805 * Another stop or continue happened while we
1806 * didn't have the lock. We can just swallow this
1807 * signal now. If we raced with a SIGCONT, that
1808 * should have just cleared it now. If we raced
1809 * with another processor delivering a stop signal,
1810 * then the SIGCONT that wakes us up should clear it.
1812 read_unlock(&tasklist_lock);
1816 if (sig->group_stop_count == 0) {
1817 sig->group_exit_code = signr;
1819 for (t = next_thread(current); t != current;
1822 * Setting state to TASK_STOPPED for a group
1823 * stop is always done with the siglock held,
1824 * so this check has no races.
1826 if (!t->exit_state &&
1827 !(t->state & (TASK_STOPPED|TASK_TRACED))) {
1829 signal_wake_up(t, 0);
1831 sig->group_stop_count = stop_count;
1834 /* A race with another thread while unlocked. */
1835 signr = sig->group_exit_code;
1836 stop_count = --sig->group_stop_count;
1839 current->exit_code = signr;
1840 set_current_state(TASK_STOPPED);
1841 if (stop_count == 0)
1842 sig->flags = SIGNAL_STOP_STOPPED;
1844 spin_unlock_irq(&sighand->siglock);
1845 read_unlock(&tasklist_lock);
1848 finish_stop(stop_count);
1853 * Do appropriate magic when group_stop_count > 0.
1854 * We return nonzero if we stopped, after releasing the siglock.
1855 * We return zero if we still hold the siglock and should look
1856 * for another signal without checking group_stop_count again.
1858 static inline int handle_group_stop(void)
1862 if (current->signal->group_exit_task == current) {
1864 * Group stop is so we can do a core dump,
1865 * We are the initiating thread, so get on with it.
1867 current->signal->group_exit_task = NULL;
1871 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1873 * Group stop is so another thread can do a core dump,
1874 * or else we are racing against a death signal.
1875 * Just punt the stop so we can get the next signal.
1880 * There is a group stop in progress. We stop
1881 * without any associated signal being in our queue.
1883 stop_count = --current->signal->group_stop_count;
1884 if (stop_count == 0)
1885 current->signal->flags = SIGNAL_STOP_STOPPED;
1886 current->exit_code = current->signal->group_exit_code;
1887 set_current_state(TASK_STOPPED);
1888 spin_unlock_irq(¤t->sighand->siglock);
1889 finish_stop(stop_count);
1893 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
1894 struct pt_regs *regs, void *cookie)
1896 sigset_t *mask = ¤t->blocked;
1900 spin_lock_irq(¤t->sighand->siglock);
1902 struct k_sigaction *ka;
1904 if (unlikely(current->signal->group_stop_count > 0) &&
1905 handle_group_stop())
1908 signr = dequeue_signal(current, mask, info);
1911 break; /* will return 0 */
1913 if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
1914 ptrace_signal_deliver(regs, cookie);
1916 /* Let the debugger run. */
1917 ptrace_stop(signr, signr, info);
1919 /* We're back. Did the debugger cancel the sig or group_exit? */
1920 signr = current->exit_code;
1921 if (signr == 0 || current->signal->flags & SIGNAL_GROUP_EXIT)
1924 current->exit_code = 0;
1926 /* Update the siginfo structure if the signal has
1927 changed. If the debugger wanted something
1928 specific in the siginfo structure then it should
1929 have updated *info via PTRACE_SETSIGINFO. */
1930 if (signr != info->si_signo) {
1931 info->si_signo = signr;
1933 info->si_code = SI_USER;
1934 info->si_pid = current->parent->pid;
1935 info->si_uid = current->parent->uid;
1938 /* If the (new) signal is now blocked, requeue it. */
1939 if (sigismember(¤t->blocked, signr)) {
1940 specific_send_sig_info(signr, info, current);
1945 ka = ¤t->sighand->action[signr-1];
1946 if (ka->sa.sa_handler == SIG_IGN) /* Do nothing. */
1948 if (ka->sa.sa_handler != SIG_DFL) {
1949 /* Run the handler. */
1952 if (ka->sa.sa_flags & SA_ONESHOT)
1953 ka->sa.sa_handler = SIG_DFL;
1955 break; /* will return non-zero "signr" value */
1959 * Now we are doing the default action for this signal.
1961 if (sig_kernel_ignore(signr)) /* Default is nothing. */
1964 /* Init gets no signals it doesn't want. */
1965 if (current->pid == 1)
1968 if (sig_kernel_stop(signr)) {
1970 * The default action is to stop all threads in
1971 * the thread group. The job control signals
1972 * do nothing in an orphaned pgrp, but SIGSTOP
1973 * always works. Note that siglock needs to be
1974 * dropped during the call to is_orphaned_pgrp()
1975 * because of lock ordering with tasklist_lock.
1976 * This allows an intervening SIGCONT to be posted.
1977 * We need to check for that and bail out if necessary.
1979 if (signr != SIGSTOP) {
1980 spin_unlock_irq(¤t->sighand->siglock);
1982 /* signals can be posted during this window */
1984 if (is_orphaned_pgrp(process_group(current)))
1987 spin_lock_irq(¤t->sighand->siglock);
1990 if (likely(do_signal_stop(signr))) {
1991 /* It released the siglock. */
1996 * We didn't actually stop, due to a race
1997 * with SIGCONT or something like that.
2002 spin_unlock_irq(¤t->sighand->siglock);
2005 * Anything else is fatal, maybe with a core dump.
2007 current->flags |= PF_SIGNALED;
2008 if (sig_kernel_coredump(signr)) {
2010 * If it was able to dump core, this kills all
2011 * other threads in the group and synchronizes with
2012 * their demise. If we lost the race with another
2013 * thread getting here, it set group_exit_code
2014 * first and our do_group_exit call below will use
2015 * that value and ignore the one we pass it.
2017 do_coredump((long)signr, signr, regs);
2021 * Death signals, no core dump.
2023 do_group_exit(signr);
2026 spin_unlock_irq(¤t->sighand->siglock);
2030 EXPORT_SYMBOL(recalc_sigpending);
2031 EXPORT_SYMBOL_GPL(dequeue_signal);
2032 EXPORT_SYMBOL(flush_signals);
2033 EXPORT_SYMBOL(force_sig);
2034 EXPORT_SYMBOL(kill_pg);
2035 EXPORT_SYMBOL(kill_proc);
2036 EXPORT_SYMBOL(ptrace_notify);
2037 EXPORT_SYMBOL(send_sig);
2038 EXPORT_SYMBOL(send_sig_info);
2039 EXPORT_SYMBOL(sigprocmask);
2040 EXPORT_SYMBOL(block_all_signals);
2041 EXPORT_SYMBOL(unblock_all_signals);
2045 * System call entry points.
2048 asmlinkage long sys_restart_syscall(void)
2050 struct restart_block *restart = ¤t_thread_info()->restart_block;
2051 return restart->fn(restart);
2054 long do_no_restart_syscall(struct restart_block *param)
2060 * We don't need to get the kernel lock - this is all local to this
2061 * particular thread.. (and that's good, because this is _heavily_
2062 * used by various programs)
2066 * This is also useful for kernel threads that want to temporarily
2067 * (or permanently) block certain signals.
2069 * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
2070 * interface happily blocks "unblockable" signals like SIGKILL
2073 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
2078 spin_lock_irq(¤t->sighand->siglock);
2079 old_block = current->blocked;
2083 sigorsets(¤t->blocked, ¤t->blocked, set);
2086 signandsets(¤t->blocked, ¤t->blocked, set);
2089 current->blocked = *set;
2094 recalc_sigpending();
2095 spin_unlock_irq(¤t->sighand->siglock);
2097 *oldset = old_block;
2102 sys_rt_sigprocmask(int how, sigset_t __user *set, sigset_t __user *oset, size_t sigsetsize)
2104 int error = -EINVAL;
2105 sigset_t old_set, new_set;
2107 /* XXX: Don't preclude handling different sized sigset_t's. */
2108 if (sigsetsize != sizeof(sigset_t))
2113 if (copy_from_user(&new_set, set, sizeof(*set)))
2115 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
2117 error = sigprocmask(how, &new_set, &old_set);
2123 spin_lock_irq(¤t->sighand->siglock);
2124 old_set = current->blocked;
2125 spin_unlock_irq(¤t->sighand->siglock);
2129 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2137 long do_sigpending(void __user *set, unsigned long sigsetsize)
2139 long error = -EINVAL;
2142 if (sigsetsize > sizeof(sigset_t))
2145 spin_lock_irq(¤t->sighand->siglock);
2146 sigorsets(&pending, ¤t->pending.signal,
2147 ¤t->signal->shared_pending.signal);
2148 spin_unlock_irq(¤t->sighand->siglock);
2150 /* Outside the lock because only this thread touches it. */
2151 sigandsets(&pending, ¤t->blocked, &pending);
2154 if (!copy_to_user(set, &pending, sigsetsize))
2162 sys_rt_sigpending(sigset_t __user *set, size_t sigsetsize)
2164 return do_sigpending(set, sigsetsize);
2167 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
2169 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
2173 if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
2175 if (from->si_code < 0)
2176 return __copy_to_user(to, from, sizeof(siginfo_t))
2179 * If you change siginfo_t structure, please be sure
2180 * this code is fixed accordingly.
2181 * It should never copy any pad contained in the structure
2182 * to avoid security leaks, but must copy the generic
2183 * 3 ints plus the relevant union member.
2185 err = __put_user(from->si_signo, &to->si_signo);
2186 err |= __put_user(from->si_errno, &to->si_errno);
2187 err |= __put_user((short)from->si_code, &to->si_code);
2188 switch (from->si_code & __SI_MASK) {
2190 err |= __put_user(from->si_pid, &to->si_pid);
2191 err |= __put_user(from->si_uid, &to->si_uid);
2194 err |= __put_user(from->si_tid, &to->si_tid);
2195 err |= __put_user(from->si_overrun, &to->si_overrun);
2196 err |= __put_user(from->si_ptr, &to->si_ptr);
2199 err |= __put_user(from->si_band, &to->si_band);
2200 err |= __put_user(from->si_fd, &to->si_fd);
2203 err |= __put_user(from->si_addr, &to->si_addr);
2204 #ifdef __ARCH_SI_TRAPNO
2205 err |= __put_user(from->si_trapno, &to->si_trapno);
2209 err |= __put_user(from->si_pid, &to->si_pid);
2210 err |= __put_user(from->si_uid, &to->si_uid);
2211 err |= __put_user(from->si_status, &to->si_status);
2212 err |= __put_user(from->si_utime, &to->si_utime);
2213 err |= __put_user(from->si_stime, &to->si_stime);
2215 case __SI_RT: /* This is not generated by the kernel as of now. */
2216 case __SI_MESGQ: /* But this is */
2217 err |= __put_user(from->si_pid, &to->si_pid);
2218 err |= __put_user(from->si_uid, &to->si_uid);
2219 err |= __put_user(from->si_ptr, &to->si_ptr);
2221 default: /* this is just in case for now ... */
2222 err |= __put_user(from->si_pid, &to->si_pid);
2223 err |= __put_user(from->si_uid, &to->si_uid);
2232 sys_rt_sigtimedwait(const sigset_t __user *uthese,
2233 siginfo_t __user *uinfo,
2234 const struct timespec __user *uts,
2243 /* XXX: Don't preclude handling different sized sigset_t's. */
2244 if (sigsetsize != sizeof(sigset_t))
2247 if (copy_from_user(&these, uthese, sizeof(these)))
2251 * Invert the set of allowed signals to get those we
2254 sigdelsetmask(&these, sigmask(SIGKILL)|sigmask(SIGSTOP));
2258 if (copy_from_user(&ts, uts, sizeof(ts)))
2260 if (ts.tv_nsec >= 1000000000L || ts.tv_nsec < 0
2265 spin_lock_irq(¤t->sighand->siglock);
2266 sig = dequeue_signal(current, &these, &info);
2268 timeout = MAX_SCHEDULE_TIMEOUT;
2270 timeout = (timespec_to_jiffies(&ts)
2271 + (ts.tv_sec || ts.tv_nsec));
2274 /* None ready -- temporarily unblock those we're
2275 * interested while we are sleeping in so that we'll
2276 * be awakened when they arrive. */
2277 current->real_blocked = current->blocked;
2278 sigandsets(¤t->blocked, ¤t->blocked, &these);
2279 recalc_sigpending();
2280 spin_unlock_irq(¤t->sighand->siglock);
2282 timeout = schedule_timeout_interruptible(timeout);
2285 spin_lock_irq(¤t->sighand->siglock);
2286 sig = dequeue_signal(current, &these, &info);
2287 current->blocked = current->real_blocked;
2288 siginitset(¤t->real_blocked, 0);
2289 recalc_sigpending();
2292 spin_unlock_irq(¤t->sighand->siglock);
2297 if (copy_siginfo_to_user(uinfo, &info))
2310 sys_kill(int pid, int sig)
2312 struct siginfo info;
2314 info.si_signo = sig;
2316 info.si_code = SI_USER;
2317 info.si_pid = current->tgid;
2318 info.si_uid = current->uid;
2320 return kill_something_info(sig, &info, pid);
2323 static int do_tkill(int tgid, int pid, int sig)
2326 struct siginfo info;
2327 struct task_struct *p;
2330 info.si_signo = sig;
2332 info.si_code = SI_TKILL;
2333 info.si_pid = current->tgid;
2334 info.si_uid = current->uid;
2336 read_lock(&tasklist_lock);
2337 p = find_task_by_pid(pid);
2338 if (p && (tgid <= 0 || p->tgid == tgid)) {
2339 error = check_kill_permission(sig, &info, p);
2341 * The null signal is a permissions and process existence
2342 * probe. No signal is actually delivered.
2344 if (!error && sig && p->sighand) {
2345 spin_lock_irq(&p->sighand->siglock);
2346 handle_stop_signal(sig, p);
2347 error = specific_send_sig_info(sig, &info, p);
2348 spin_unlock_irq(&p->sighand->siglock);
2351 read_unlock(&tasklist_lock);
2357 * sys_tgkill - send signal to one specific thread
2358 * @tgid: the thread group ID of the thread
2359 * @pid: the PID of the thread
2360 * @sig: signal to be sent
2362 * This syscall also checks the tgid and returns -ESRCH even if the PID
2363 * exists but it's not belonging to the target process anymore. This
2364 * method solves the problem of threads exiting and PIDs getting reused.
2366 asmlinkage long sys_tgkill(int tgid, int pid, int sig)
2368 /* This is only valid for single tasks */
2369 if (pid <= 0 || tgid <= 0)
2372 return do_tkill(tgid, pid, sig);
2376 * Send a signal to only one task, even if it's a CLONE_THREAD task.
2379 sys_tkill(int pid, int sig)
2381 /* This is only valid for single tasks */
2385 return do_tkill(0, pid, sig);
2389 sys_rt_sigqueueinfo(int pid, int sig, siginfo_t __user *uinfo)
2393 if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
2396 /* Not even root can pretend to send signals from the kernel.
2397 Nor can they impersonate a kill(), which adds source info. */
2398 if (info.si_code >= 0)
2400 info.si_signo = sig;
2402 /* POSIX.1b doesn't mention process groups. */
2403 return kill_proc_info(sig, &info, pid);
2407 do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
2409 struct k_sigaction *k;
2411 if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
2414 k = ¤t->sighand->action[sig-1];
2416 spin_lock_irq(¤t->sighand->siglock);
2417 if (signal_pending(current)) {
2419 * If there might be a fatal signal pending on multiple
2420 * threads, make sure we take it before changing the action.
2422 spin_unlock_irq(¤t->sighand->siglock);
2423 return -ERESTARTNOINTR;
2432 * "Setting a signal action to SIG_IGN for a signal that is
2433 * pending shall cause the pending signal to be discarded,
2434 * whether or not it is blocked."
2436 * "Setting a signal action to SIG_DFL for a signal that is
2437 * pending and whose default action is to ignore the signal
2438 * (for example, SIGCHLD), shall cause the pending signal to
2439 * be discarded, whether or not it is blocked"
2441 if (act->sa.sa_handler == SIG_IGN ||
2442 (act->sa.sa_handler == SIG_DFL &&
2443 sig_kernel_ignore(sig))) {
2445 * This is a fairly rare case, so we only take the
2446 * tasklist_lock once we're sure we'll need it.
2447 * Now we must do this little unlock and relock
2448 * dance to maintain the lock hierarchy.
2450 struct task_struct *t = current;
2451 spin_unlock_irq(&t->sighand->siglock);
2452 read_lock(&tasklist_lock);
2453 spin_lock_irq(&t->sighand->siglock);
2455 sigdelsetmask(&k->sa.sa_mask,
2456 sigmask(SIGKILL) | sigmask(SIGSTOP));
2457 rm_from_queue(sigmask(sig), &t->signal->shared_pending);
2459 rm_from_queue(sigmask(sig), &t->pending);
2460 recalc_sigpending_tsk(t);
2462 } while (t != current);
2463 spin_unlock_irq(¤t->sighand->siglock);
2464 read_unlock(&tasklist_lock);
2469 sigdelsetmask(&k->sa.sa_mask,
2470 sigmask(SIGKILL) | sigmask(SIGSTOP));
2473 spin_unlock_irq(¤t->sighand->siglock);
2478 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
2484 oss.ss_sp = (void __user *) current->sas_ss_sp;
2485 oss.ss_size = current->sas_ss_size;
2486 oss.ss_flags = sas_ss_flags(sp);
2495 if (!access_ok(VERIFY_READ, uss, sizeof(*uss))
2496 || __get_user(ss_sp, &uss->ss_sp)
2497 || __get_user(ss_flags, &uss->ss_flags)
2498 || __get_user(ss_size, &uss->ss_size))
2502 if (on_sig_stack(sp))
2508 * Note - this code used to test ss_flags incorrectly
2509 * old code may have been written using ss_flags==0
2510 * to mean ss_flags==SS_ONSTACK (as this was the only
2511 * way that worked) - this fix preserves that older
2514 if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
2517 if (ss_flags == SS_DISABLE) {
2522 if (ss_size < MINSIGSTKSZ)
2526 current->sas_ss_sp = (unsigned long) ss_sp;
2527 current->sas_ss_size = ss_size;
2532 if (copy_to_user(uoss, &oss, sizeof(oss)))
2541 #ifdef __ARCH_WANT_SYS_SIGPENDING
2544 sys_sigpending(old_sigset_t __user *set)
2546 return do_sigpending(set, sizeof(*set));
2551 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
2552 /* Some platforms have their own version with special arguments others
2553 support only sys_rt_sigprocmask. */
2556 sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset)
2559 old_sigset_t old_set, new_set;
2563 if (copy_from_user(&new_set, set, sizeof(*set)))
2565 new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
2567 spin_lock_irq(¤t->sighand->siglock);
2568 old_set = current->blocked.sig[0];
2576 sigaddsetmask(¤t->blocked, new_set);
2579 sigdelsetmask(¤t->blocked, new_set);
2582 current->blocked.sig[0] = new_set;
2586 recalc_sigpending();
2587 spin_unlock_irq(¤t->sighand->siglock);
2593 old_set = current->blocked.sig[0];
2596 if (copy_to_user(oset, &old_set, sizeof(*oset)))
2603 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
2605 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
2607 sys_rt_sigaction(int sig,
2608 const struct sigaction __user *act,
2609 struct sigaction __user *oact,
2612 struct k_sigaction new_sa, old_sa;
2615 /* XXX: Don't preclude handling different sized sigset_t's. */
2616 if (sigsetsize != sizeof(sigset_t))
2620 if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
2624 ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
2627 if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
2633 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
2635 #ifdef __ARCH_WANT_SYS_SGETMASK
2638 * For backwards compatibility. Functionality superseded by sigprocmask.
2644 return current->blocked.sig[0];
2648 sys_ssetmask(int newmask)
2652 spin_lock_irq(¤t->sighand->siglock);
2653 old = current->blocked.sig[0];
2655 siginitset(¤t->blocked, newmask & ~(sigmask(SIGKILL)|
2657 recalc_sigpending();
2658 spin_unlock_irq(¤t->sighand->siglock);
2662 #endif /* __ARCH_WANT_SGETMASK */
2664 #ifdef __ARCH_WANT_SYS_SIGNAL
2666 * For backwards compatibility. Functionality superseded by sigaction.
2668 asmlinkage unsigned long
2669 sys_signal(int sig, __sighandler_t handler)
2671 struct k_sigaction new_sa, old_sa;
2674 new_sa.sa.sa_handler = handler;
2675 new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
2677 ret = do_sigaction(sig, &new_sa, &old_sa);
2679 return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
2681 #endif /* __ARCH_WANT_SYS_SIGNAL */
2683 #ifdef __ARCH_WANT_SYS_PAUSE
2688 current->state = TASK_INTERRUPTIBLE;
2690 return -ERESTARTNOHAND;
2695 void __init signals_init(void)
2698 kmem_cache_create("sigqueue",
2699 sizeof(struct sigqueue),
2700 __alignof__(struct sigqueue),
2701 SLAB_PANIC, NULL, NULL);